1. Field of the Disclosure
The present disclosure relates to a light emitting diode assembly and a liquid crystal display device including the same, and more particularly, to a light emitting diode assembly for realizing a liquid crystal display device having a narrow bezel and a slim thickness.
2. Discussion of the Related Art
Liquid crystal display (LCD) devices are widely used as monitors of notebook computers, monitors of personal computers and televisions due to excellent reproduction of moving images and high contrast ratio. LCD devices use the optical anisotropy and polarization properties of liquid crystal molecules of a liquid crystal layer to produce an image.
An LCD device includes two substrates spaced apart from each other and facing each other as well as a liquid crystal layer interposed between the two substrates. The alignment direction of the liquid crystal molecules is controlled by varying the intensity of an electric field applied to the liquid crystal layer, thus changing the transmittance of light through the liquid crystal layer.
The LCD devices require an additional light source because the LCD devices are not self-luminescent. Therefore, a backlight unit is disposed at a rear side of a liquid crystal (LC) panel and emits light into the LC panel to display images.
Backlight units are in general classified as edge type or direct type according to the position of the light source with respect to an LC panel. In edge-type backlight units, a light guide plate is disposed under the LC panel, and one or a pair of lamps are disposed at one side or at each of two sides of the light guide plate. Light from the lamps is refracted and reflected by the light guide plate to be indirectly provided to the LC panel. In direct-type backlight units, a plurality of lamps is disposed directly under the LC panel, and light from the lamps is directly provided to the LC panel.
Backlight units include cold cathode fluorescent lamps (CCFLs), external electrode fluorescent lamps (EEFLs), and light emitting diodes (LEDs) as a light source. Among these, LEDs have been widely used due to their small sizes, low power consumption, and high reliability.
FIG. 1 is a cross-sectional view of illustrating an LCD device according to the related art, and FIG. 2 is a perspective view of illustrating an LED assembly included in the LCD device of FIG. 1.
In FIG. 1, the related art LCD device includes a liquid crystal panel 10 comprising first and second substrates 12 and 14 and a backlight unit 20 at a rear side of the liquid crystal panel 10.
The liquid crystal panel 10 and the backlight unit 20 are modularized with a top cover 40, a support main 30 and a cover bottom 50. Edges of the liquid crystal panel 10 and the backlight unit 20 are surrounded by the support main 30 having a rectangular frame shape. The top cover 40 covers edges of a front surface of the liquid crystal panel 10, and the cover bottom 50 covers a rear surface of the backlight unit 20. The top cover 40 and the cover bottom 50 are combined with the support main 30 to thereby constitute one-united body.
The liquid crystal panel 10 displays images and includes first and second substrates 12 and 14 facing and attached to each other with a liquid crystal layer (not shown) interposed therebetween.
Polarizers 19a and 19b are attached at outer surfaces of the first and second substrates 12 and 14, respectively, and selectively transmit specific light.
The backlight unit 20 includes an LED assembly 29, a reflection sheet 25 over the cover bottom 50, a light guide plate 23 over the reflection sheet 25 and a plurality of optical sheets 21 over the light guide plate 23. As shown in FIG. 2, the LED assembly 29 includes LEDs 29a and a printed circuit board 29b on which the LEDs 29a are mounted with a predetermined distance d between adjacent LEDs 29a. 
At this time, circuit patterns 29b-1, which are formed over the printed circuit board 29b, are electrically connected to electrode leads 29a-1, which are formed at both sides of each of the LEDs 29a through solder (not shown).
Meanwhile, light emitted from each of the LEDs 29a is incident on an inside of the light guide plate 23 and is mixed to produce uniform light. At this time, a light mixing length l is required.
That is, the light mixing length l is a length needed to produce uniform light by overlap and mixture of light emitted from each of the LEDs 29a because the LEDs 29a are mounted on the printed circuit board 29b and spaced apart from each other with the predetermined distance therebetween. Within the light mixing length l, hot spots may be caused due to dark areas where the light emitted from the LEDs 29a does not reach, and thus the top cover 40 corresponding to the bezel needs to be extended by the light mixing length l. Accordingly, the bezel width depends on the light mixing length l.
Recently, LCD devices have been required to have a large display area and a narrow bezel. However, the light mixing length l limits the bezel width and the thickness of the LCD devices.